3rd-century births

Roman emperor from 306 to 337 and first to convert to Christianity (272–337)

Christian saint and martyr (died 303)

Diophantus of Alexandria () (; ) was a Greek mathematician who was the author of the Arithmetica in thirteen books, ten of which are still extant, made up of arithmetical problems that are solved through algebraic equations.

Pope and bishop of Rome (tenure 296-304)

Roman emperor (250-306)

pope

Maximian (; ), nicknamed Herculius, was Roman emperor from 286 to 305. He was Caesar from 285 to 286, then Augustus from 286 to 305. He shared the latter title with his co-emperor and superior, Diocletian, whose political brain complemented Maximian's military brawn. Maximian established his residence at Trier but spent most of his time on campaign. In late 285, he suppressed rebels in Gaul known as the Bagaudae. From 285 to 288, he fought against Germanic tribes along the Rhine frontier. Together with Diocletian, he launched a scorched earth campaign deep into Alamannic territory in 288, refo

Roman Catholic saint, martyr and patron saint of music

early 4th-century saint and bishop

thumb|A Roman Antoninianus|radiate produced in 283 depicting Emperor Carinus. From the collection of [[York Museums Trust. Legend: M. AVR. CARINVS NOB. CAES.]]

early 4th century Roman emperor

Roman emperor from 310 to 313

Lucius Caecilius Firmianus Lactantius () was an early Christian author who became an advisor to Roman emperor Constantine I, guiding his Christian religious policy in its initial stages of emergence, and a tutor to his son Crispus. His most important work is the Institutiones Divinae ("The Divine Institutes"), an apologetic treatise intended to establish the reasonableness and truth of Christianity to pagan critics.

saint (275–304) usually shown with a dragon (292–307)

The third Sasanian emperor (270–271)

eighth Sasanian emperor (302–309)

The fourth Sasanian emperor (271–274)

twins and early Christian martyrs born in Arabia

Narseh (also spelled Narses or Narseus; ) was the seventh King of Kings of Sasanian Iran from 293 to 303. The youngest son of Shapur I (), Narseh served as the governor of Sakastan, Hind and Turan under his father. Shapur I was eventually succeeded by his son Hormizd I (), who died after a reign of one year. Shapur I's eldest son Bahram I, who had never been considered as a candidate for succession to the throne by his father, ascended the throne with the aid of the powerful Zoroastrian priest Kartir. He then made a settlement with Narseh to give up his entitlement to the throne in return for

Januarius ( ; ; Neapolitan and ), also known as , was Bishop of Benevento and is a martyr and saint of the Catholic Church. While no contemporary sources on his life are preserved, later sources and legends say he died during the Great Persecution, which ended with Diocletian's retirement in 305.

3rd-century Bishop of Paris and saint

fifth Sasanian emperor (274–293)

saint and martyr

Sammarinese saint

3rd or 4th-century Sicilian saint

sixth Sasanian emperor (293)

Christian martyr (died 306)

Patriarch of Antioch

Christian saint and martyr

Aureolus was a Roman military commander during the reign of Emperor Gallienus before he attempted to usurp the Roman Empire. After turning against Gallienus, Aureolus was killed during the political turmoil that surrounded the Emperor's assassination in a conspiracy orchestrated by his senior officers. Aureolus is known as one of the Thirty Tyrants and is referenced in ancient sources including the Historia Augusta, Zonaras' epitome and Zosimus' Historia Nova.

Patriarch of Antioch

The ninth Sasanian emperor (309)

3rd century Christian ecclesiastical writer

son of Roman Emperor Constantius Chlorus (died 337)

Euphemia (; 'well-spoken [of]'), known as Euphemia the All-praised in the Eastern Orthodox Church, was a virgin martyr, who died for her faith at Chalcedon in 303 AD.

Roman martyrs and early Christian saints

Christian bishop and martyr

usurper of the Roman Empire

Eutropia (Greek: Εύτροπία; died after 325) was a Roman empress of Syrian origin, the wife of Emperor Maximian.

Expeditus (died 303), also known as Expedite, was said to have been a Roman centurion in Armenia who was martyred around April 303 in what is now Turkey, for converting to Christianity. Considered the patron saint of urgent causes, he is also known as the saint of time; he was commemorated by the Catholic Church on 19 April.

Syrian saint

Presbyter of Caesarea

Augusta of the Eastern Roman Empire (266–315)

Censorinus () was a Roman grammarian and miscellaneous writer.

Bishop of Byzantium and the first bishop of Constantinople

Egyptian alchemist

Cyriacus (, fl. 303 AD), sometimes Anglicized as Cyriac, according to Christian tradition, is a Christian martyr who was killed in the Diocletianic Persecution. He is one of twenty-seven saints, most of them martyrs, who bear this name, of whom only seven are honoured by a specific mention of their names in Roman Martyrology.

Christian patron saints of cobblers, tanners, and leather workers

christian martyr

Kartir (also spelled Karder, Karter and Kerdir; Middle Persian: 𐭪𐭫𐭲𐭩𐭫 Kardīr) was a powerful and influential Zoroastrian priest during the reigns of four Sasanian kings in the 3rd century. His name is cited in the inscriptions of Shapur I (as well as in the Res Gestae Divi Saporis) and the Paikuli inscription of Narseh. Kartir also had inscriptions of his own made in the present-day Fars province (then known as Pars). His inscriptions narrates his rise to power throughout the reigns of Shapur I (), Hormizd I (), Bahram I (), and Bahram II (). During the brief reign of Bahram II's son and

Amelius Gentilianus (; ), was a Neoplatonist philosopher and writer of the second half of the 3rd century.

Roman empress as the consort of Maxentius

priest and saint

Proculus (died c. 281) was a Roman usurper, one of the "minor pretenders" according to Historia Augusta, who would have taken the purple against Emperor Probus in 280. This is now disputed.

Christian martyrs of the 3rd century

Italian martyr and saint

pair of Christians martyred in 304

son of Roman Emperor Maximinus Thrax

Christian saint

Gallo-Roman saint